One thing I've found with my 770 is I am using it as an ipod much more than I had expected. It plays music well and I also have a lot of music videos that I can play on it. Right now I have a 1 GB card, but was wondering if I had more than one, say one with music on it and one with videos on it, can I simply "hot-swap" them or do I have to power down to switch cards?